Primary non-necrotizing granulomatous hypophysitis mimicking pituitary adenomas

The authors review their experience in the endoscopic endonasal transsphenoidal treatment of 5 patients, finally diagnosed as primary hypophysitis but initially assumed to be pituitary adenomas.

A retrospective study was undertaken to review 5 cases of primary non-necrotizing granulomatous hypophysitis (1.61%) through 310 endoscopic transsphenoidally operated cases with the diagnosis of pituitary adenoma between 2009 and 2013. All 5 cases were female without any background of autoimmunity or recent pregnancy. The initial presumptive diagnosis was pituitary adenoma for all patients. The endocrinological diagnoses of the patients were suspected Cushing's Disease, anterior pituitary deficiency with hyponatremia, hyperprolactinemia, and acromegaly. One of the patients had normal hormonal levels. All patients had macroadenomas including one invasive adenoma with skull base involvement. One of the patients (20%) had visual field defects. All patients underwent endoscopic endonasal transsphenoidal surgery (EETS).

All patients had improvement of hormonal levels postoperatively except the one with anterior pituitary deficiency who required long term hormone replacement after the surgery. Mean follow-up duration was 14.8 months.

Primary granulomatous hypophysitis without any known etiological factors is very rare in the literature. It can mimic pituitary adenomas in radiological and endocrinological aspects. EETS is an effective and safe treatment especially for visual and compression symptoms.